Phonograph needle



Oct. 29, 1929. w. s. KNOX ET AL. 1,733,608

PHQNOGRAPH NEEDLE Filed Aug B, 1928 MLLIAM G. K-0x ALEXANDER G. Russsu. BY X M/P lNl/ENTU/PS:

Patented- Oct. 29; 1929 UNITED STATES I PATENT OFFICE WILLIAI G. KNOX, OI IANHASSET, N-EW YORK, AND ALEXANDER G. BUSSEIJL, 013

BED BANK, NEW JERSEY, ASSIGNORS TO BELL TELEPHONE LABORATORIES, IN- CORPORATED, 01 NEW YORK, 11'. Y., A CORPORATION OF NEW YORK rnonocmn NEEDLE Application flledAugust 1928. Serial No. 288,257.

15 this kind may be conveniently manufactured by electroplating a thin. coatingof nickel on asuitably proportioned conical mandrel and then stripping off the nickel cone .so deposited. To prevent burning or treeing 29 during the plating process the needle point is protected by a guard ring of wire electrically connected to the needle. The point ofthe cone is properly contoured to fit the record grooves and then a thin coating of chromium is deposited to make the needle semipermanent. The other end of the needle may be fitted with a threaded plug or other means suitable for attaching the needle to the reproducer. y

In the drawing Fig. 1 is a side view showing a rack carrymg several mandrels inthe plating bath;

Fig. 2 is a detail view of the guard rings indicated in Fig. 1;

Fig. 3 is a side viewof the cones immersed in the chromium bath; and

Fig. 4 shows a completed needle, accord ing to the process of this invention.

A plating bath which has been found suitable for the pur ose of this invention is that known as the ads'en nickel bath which is described b Dorsey in Industrial and Engineering hemistry, for November, 1927, at page 1219. In the present case this bath is operated preferably at a tem erature of from to C. andcthe p is maintained at 5.6 'by adding sulphuric acid or nickelous hydrate as required.

The mandrels used in this process must 50 be treated before immersion in the plating bath to prevent the deposited nickel from adhering to them. This may be done in various ways such as by the selenium treatment disclosed in U. S. Patent 1,359,972, igranted to T. A. Edison, November 23, 1920, y reversing'the current for a few seconds as described in British Patent 27 5,221 or] by bufing the mandrel on a soft cloth wheel using a suitable grease such as tripoli compound and wipin off all the visible grease to leave a very thin film u on which a poorly adherent coating of nic el may be plated.

Referring now to Fig. 1, a number of mandrels suchas 1, 1 havin been'treated in one of the ways outlined a ove, are secured to rack 2 and immersed in the Madsembath 3 to a depth of about 1 as indicated.

The guarding or-shielding rings 4 are preferably about 4 inside diameter and may be made from a single length of No. 14 gauge bare copper wire 5, as shown in Fig. 2. With this arrangement and a plating current of about one ampere er mandrel suitable cones of-about 2 mils t ickness at the base and about 4 mils near the point are obtained.

These cones arereadily removed from the mandrels by burnishing them on a steel wheel.

I Before the chromium plating is applied tov the points theyare ground to the proper contour for engaging record grooves. 9 is then fastened on a peg .6 of. the rack 7 Each cone by a piece of soft copper wire 8, as-shown in Fig. 3. After cleaning the points and preparing the surface to be plated in any well known manner, such as by the use of the alkali f j electrocleaner and the Madsen cleaning progedlure, the cones are ready for the chromium at The Sargent bath containing 250 grams per litre of chromic acid and four grams per litre of chromium sulphate has been found satisfactor Lead anodes (not shown) are used oneit er side of the rack 7 and plating is continued for six hours at a current of about ampere per cone, with the cones immersed to a depth of about A". coating of chromium about two mils thick at the needle point. A straight iece of No. 23 gauge copper wire 10 spaced 9. out from This results in 'a' c the points as shown in Fig. 3 has sufiicient guarding action in this case.

These needles are then cut to the proper len h and a threaded (plug 11 is fitted into 5 the ase of each to rovi eaconvenient means of attaching it to t e reproducer, as shown in ilthough this method has been described in detail and with reference to a particular application, it is obvious that many modifications may be made without departing from the spirit and scope of this invention.

What is claimed is a 1. The method of making a thin hollow cone which consists of electroplating metal on a suitably shaped mandrel and guarding the point of the mandrel during the plating process with a conductor electrically connect ed to the cone.

2. The method of making a phonograph needle which consists of electroplatin' a cone of metal on a suitably shaped mandre stripping the cone from the mandrel, contouring the point of the cone to fit a record groove and adapting the base of the cone for attachment to a p onographic device.

3. The method of making a phonograph needle which consists in electroplating a thin cone of nickel on a suitably shaped mandrel,

o stripping the cone from the mandrel, contouring the point of the cone to fit a record groove, plating chromium on the point of said cone and adaptin the base of thecone for attachment to a p onogra-phic device.

4. In the art of electrodepositing metal on an electrode the method of'manufacturing a hollow conical phonograph needle which consists of treating said electrode to cause imperfect adhesion of the deposited metal, de:

' positing a coating of metal on the electrode the thickness of the coating at the 1point of the'electrode being determined by t e proximity of a guarding member electrically connected to said electrode.

5. The method of making a phonograph needle which consists of depositing metal in the form of a cone on a mandrel, the thickiiess of the deposit at the point of said cone being governed by a'guarding conductor electrically connected to the mandrel, strip ing the cone from the mandrel, contouring t e point to fit a reFord groove and chromium plating thecontoured point. 7

In witness whereof, we hereunto subscribe our names this 6th day of Au st, 1928. p

" ALEXANDER RUSSELL.

WILLIAM KNOX. 

